In conventional hip arthroplasty, it is desirable to form a bone plug from the resected (severed) femoral head, and use that bone plug as a dam for the cement inserted into the femur medullary canal to hold the prosthesis in place. The cutting of the bone plug of the desired size depending upon the particular femoral medullary canal into which it is to be inserted, and the positioning of the bone plug at the proper depth, conventionally require relatively complicated procedures and equipment, and are relatively time consuming. According to the present invention a method of performing hip arthroplasty, and apparatus facilitating practice of the method, are provided which simplify the procedures with respect to desired formation and placement of the bone plug, and reduce the time consumed.
According to one aspect of the present invention, an apparatus is provided for facilitating hip arthroplasty or the like. That apparatus includes: A rod having first and second enlarged generally disc-shaped ends, each end disc having a predetermined diameter, the first end disc diameter being different than the second end disc diameter. Linear calibrating indicia formed on the rod at predetermined distances from each of the ends thereof. Correlating indicia associated with each of the ends of the rod, the indicia for the first end distinct from that for the second end. First and second hollow bone cutting tools of different effective internal diameter, the first tool having an internal diameter substantially identical to the diameter of the rod first end disc diameter, and the first tool having correlating indicia corresponding to that for the rod first end and the second tool having an effective internal diameter substantially identical to the diameter of the rod second end disc diameter, and having correlating indicia corresponding to that for the rod second end.
The correlating indicia preferably comprise colors, and preferably a plurality of rods, and twice the number of cutting tools as rods, are provided, so that the bone plug may be of the desired size. Also, a holding device for holding the resected femoral head, and for guiding the cutting tool, is provided mounted on a support, and the support is dimensioned so that it also holds the rods and tools in storage positions. A notch formed in the support is provided to hold the rod in an upright position when the rod is utilized for removing a bone plug from a cutting tool.
According to another aspect of the present invention there is provided: A support stationarily mounting a cup for receipt of a bone portion, and having a pair of rods upstanding from, and straddling, the cup. A movable holding component including means defining openings therein for receipt of the rods so that the movable component is movable toward and away from the cup guided by the rods. Affixing means for affixing the movable component to the rods at a predetermined position to thereby clamp a bone portion between the cup and the movable component. A tubular guide disposed in operative association with the movable holding component, and having an interior diameter aligned with the cup when the movable component is held in operative association with respect to the cup, receiving said rods. A plurality of differently dimensioned bone cutting tools, each bone cutting tool having an external diameter guide portion corresponding to the internal diameter of said tubular guide, and each cutting tool having a different internal diameter, corresponding to the diameter of a bone plug to be formed thereby. And, wherein the support includes surface means for mounting each of the tools in a storage position.
The rods utilized in the practice of the present invention are per se distinct from other hand tools in the art, having as they do enlarged disc-shaped ends of different diameters, distance calibrations from both ends extending along the length thereof, and color coding of the ends.
The invention further comprises a method of practicing hip arthroplasty. The method includes the following steps: (a) Severing the femur head from the femur of the hip undergoing arthroplasty. (b) Calibrating the internal diameter of the femur hollow medullary canal by inserting rod ends until a rod end is found having a disc diameter that fits snugly, but does not bind, within the medullary canal at the isthmus. (c) Simultaneously with step (b), when inserting the rod having the desired disc end diameter, determining the depth from the level of the femoral neck transection including by reading length calibrating indicia on the rod. (d) Selecting the cutting tool having correlating indicia corresponding to the correlating indicia of the selected rod disc end. (e) Utilizing the selected cutting tool, forming a bone plug from the resected femoral head. (f) Cutting the bone plug, if necessary, to the desired length. (g) Inserting the bone plug into the femoral medullary canal. (h) Utilizing the selected rod, with the selected rod end in contact with the bone plug, impacting the rod to drive the bone plug to the desired depth, as determined by reading the length calibrating indicia on the rod. (i) Inserting a suitable cement into the femoral medullary canal. (j) Disposing a prosthesis in operative association with the femoral medullary canal so that the prosthesis is held in the appropriate position by the cement; and (k) between steps (e) and (f), removing the bone plug from the cutting tool by forcing the selected rod disc end into the hollow cutting tool to contact the bone plug and move it out of the cutting tool.
It is the primary object of the present invention to provide a method for practicing hip arthroplasty, and apparatus suitable for use in the practice of hip arthroplasty, that minimize the difficulties and time associated with obtaining and positioning a desired bone plug in the femoral medullary canal. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.